#!/usr/bin/env python
# -*- coding: latin-1 -*-
# -*- coding: cp1252 -*-


hofudstoll = int(input())
arlSparn = int(input())
vextir = int(input())
fjoldiAra = int(input())

def timabil(b, a, v, ar, f):
	b = b*(1+(v/100))
	if ar > 0:
		b += a
	if ar < f:
		return timabil(b, a, v, ar+1, f)
	return b

print(timabil(hofudstoll, arlSparn, vextir, 0, fjoldiAra))


#Rounding error? amk þetta ætti að virka...
